1. Field of the Invention
The present invention relates generally to coated glass articles and more particularly to a multiple layer coating on a transparent substrate, especially in a multiple glazed window unit.
2. The Prior Art
More efficient use of energy in the heating and cooling of residential and commercial buildings can be achieved by employing insulating window units, especially those with coated surfaces which selectively reflect, transmit or absorb incident solar energy.
In U.S. Pat. No. 3,925,945, White discloses a transparent insulating building panel having a pivotally mounted frame enclosing a heat absorbing glass pane spaced from an insulating panel comprising two panes of clear glass separated by a clear air space and including apertures in the frame providing free air paths through the space between the heat absorbing glass and the insulating panel.
In U.S. application Ser. No. 791,350, filed on Apr. 27, 1977, Franz discloses a seasonally adjustable window including four spaced glass sheets, the outer sheets being selectively coated to provide a low shading coefficient in the summer position, a higher shading coefficient and a 50 percent reflectance of low temperature radiation in the winter position, and a low U-value.
In U.S. Pat. No. 3,990,784, Gelber discloses an architectural glass system having a multilayer coating comprising first and second metal layers and a dielectric material such as silicon dioxide, magnesium fluoride or aluminum oxide disposed between the metal films. Gelber teaches that the transmission of the coating can be changed independently of its reflection properties by varying the individual thicknesses of the metal layers while maintaining the ratio of the layer thicknesses constant.
In "Solar Absorptance and Thermal Emittance of Evaporated Coatings", Physics of Thin Film, Vol. 2, pp. 305-361, Drummeter and Haas discuss surface properties and temperature control in relation to objects in space and solar energy conversion. Silicon oxide and aluminum oxide films on aluminum substrates as front surface mirrors for satellites are disclosed.